Access point (ap), station (sta) and method for subcarrier scaling

ABSTRACT

Embodiments of an access point (AP), station (STA) and method for subcarrier scaling are generally described herein. The AP may transmit a high efficiency (HE) physical layer convergence procedure (PLCP) protocol data unit (PPDU) that includes a legacy long training field (L-LTF), a legacy signal (L-SIG) field, and an HE signal (HE-SIG) field. The HE-SIG may be based on HE-SIG symbols mapped to a group of HE subcarriers that includes legacy subcarriers and HE extension subcarriers. The L-LTF may be based on L-LTF pilot symbols mapped to the legacy subcarriers. The L-SIG may be based on L-SIG legacy symbols mapped to the legacy subcarriers and L-SIG extension pilot symbols mapped to the HE extension subcarriers. The AP may scale a per-subcarrier power of the L-SIG extension pilot symbols to match a per-subcarrier power of the L-LTF pilot symbols.

PRIORITY CLAIM

This application claims priority under 35 USC 119(e) to U.S. ProvisionalPatent Application Ser. No. 62/305,575, filed Mar. 9, 2016 [referencenumber P96985Z (4884,561PRV)] which is incorporated herein by referencein its entirety.

TECHNICAL FIELD

Embodiments pertain to wireless networks. Some embodiments relate towireless local area networks (WLANs) and Wi-Fi networks includingnetworks operating in accordance with the IEEE 802,11 family ofstandards, such as the IFEE 802.11ac standard or the IEEE 802.11ax studygroup (SG) (named DensiFi). Sonic embodiments relate to high-efficiency(HE) wireless or high-efficiency WLAN or Wi-Fi communications. Someembodiments relate to boosting and/or power scaling of pilot subcarriersand/or data subcarriers. Some embodiments relate to range extensionmode.

BACKGROUND

Wireless communications has been evolving toward ever increasing datarates (e.g., from IEEE 802.11a/g to IEEE 802.11n to IEEE 802.11ac). Inhigh-density deployment situations, overall system efficiency may becomemore important than higher data rates. For example, in high-densityhotspot and cellular offloading scenarios, many devices competing forthe wireless medium may have low to moderate data rate requirements(with respect to the very high data rates of IEEE 802.11ac). Arecently-formed study group for Wi-Fi evolution referred to as the IEEE802.11 High Efficiency WLAN (HEW) study group (SG) (i.e., IEEE 802.11ax)is addressing these high-density deployment scenarios.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless network in accordance with sonicembodiments;

FIG. 2 illustrates an example machine in accordance with sonicembodiments;

FIG. 3 illustrates a station (STA) in accordance with some embodimentsand an access point (AP) in accordance with some embodiments;

FIG. 4 illustrates the operation of a method of communication inaccordance with some embodiments;

FIG. 5 illustrates example packets that may be exchanged in accordancewith some embodiments; and

FIG. 6 illustrates the operation of another method of communication inaccordance with some embodiments.

DETAILED DESCRIPTION

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments may incorporate structural, logical, electrical,process, and other changes. Portions and features of sonic embodimentsmay be included in, or substituted for, those of other embodiments.Embodiments set forth in the claims encompass all available equivalentsof those claims.

FIG. 1 illustrates a wireless network in accordance with someembodiments. In some embodiments, the network 100 may be a HighEfficiency (HE) Wireless Local Area Network (WLAN) network. In someembodiments, the network 100 may be a WLAN or a Wi-Fi network. Theseembodiments are not limiting, however, as some embodiments of thenetwork 100 may include a combination of such networks. That is, thenetwork 100 may support HE devices in some cases, non HE devices in somecases, and a combination of HE devices and non HE devices in some cases.Accordingly, it is understood that although techniques described hereinmay refer to either a non HE device or to an HE device, such techniquesmay be applicable to both non HE devices and HE devices in some cases.

Referring to FIG. 1, the network 100 may include any or all of thecomponents shown, and embodiments are not limited to the number of eachcomponent shown in FIG. 1. In some embodiments, the network 100 mayinclude a master station (AP) 102 and may include any number (includingzero) of stations (STAs) 103 and/or HE devices 104. In some embodiments,the AP 102 may transmit an HE physical layer convergence procedure(PLCP) protocol data unit (PPDU) to an STA 103. The HE PPDU may includecontrol fields and/or data fields, in some cases. The STA 103 mayreceive the HE PPDU and may perform operations such as channelestimation or others as part of decoding data fields of the HE PPDU. TheSTA 103 may transmit uplink HE PPDUs to the AP, in some embodiments.These embodiments will be described in more detail below.

The AP 102 may be arranged to communicate with one or more of thecomponents shown in FIG. 1 in accordance with one or more IEEE 802.11standards (including 802.11ax and/or others), other standards and/orother communication protocols. It should be noted that embodiments arenot limited to usage of an AP 102. References herein to the AP 102 arenot limiting and references herein to the master station 102 are alsonot limiting. In some embodiments, a STA 103, HE device 104 and/or otherdevice may be configurable to operate as a master station. Accordingly,in such embodiments, operations that may be performed by the AP 102 asdescribed herein may be performed by the STA 103, HE device 104 and/orother device that is configurable to operate as the master station.

In some embodiments, one or more of the STAs 103 may be legacy stations.These embodiments are not limiting, however, as the STAs 103 may beconfigured to operate as HE devices 104 or may support HE operation insome embodiments. The master station 102 may be arranged to communicatewith the STAs 103 and/or the HE stations 104 in accordance with one ormore of the IEEE 802.11 standards, including 802.11ax and/or others. Inaccordance with some HE embodiments, an access point (AP) may operate asthe master station 102 and may be arranged to contend for a wirelessmedium (e.g., during a contention period) to receive exclusive controlof the medium for an HE control period (i.e., a. transmissionopportunity (TXOP)). The master station 102 may, for example, transmit amaster-sync or control transmission at the beginning of the HE controlperiod to indicate, among other things, which HE stations 104 arescheduled for communication during the HE control period. During the HEcontrol period, the scheduled HE stations 104 may communicate with themaster station 102 in accordance with a non-contention based multipleaccess technique. This is unlike conventional Wi-Fi communications inwhich devices communicate in accordance with a contention-basedcommunication technique, rather than a non-contention based multipleaccess technique. During the HE control period, the master station 102may communicate with HE stations 104 using one or more HE PPDUs. Duringthe HE control period, STAs 103 not operating as HE devices may refrainfrom communicating in some cases. In some embodiments, the master-synctransmission may be referred to as a control and schedule transmission.

In some embodiments, the multiple-access technique used during the HEcontrol period may be a scheduled orthogonal frequency division multipleaccess (OFDMA) technique, although this is not a requirement. In someembodiments, the multiple access technique may be a time-divisionmultiple access (TDMA) technique or a frequency division multiple access(FDMA) technique. In some embodiments, the multiple access technique maybe a space-division multiple access (SDMA) technique including amulti-user (MU) multiple-input multiple-output (MIMO) (MU-MIMO)technique. These multiple-access techniques used during the HE controlperiod may be configured for uplink or downlink data communications.

The master station 102 may also communicate with STAs 103 and/or otherlegacy stations in accordance with legacy IEEE 802.11 communicationtechniques. In some embodiments, the master station 102 may also beconfigurable to communicate with the HE stations 104 outside the HEcontrol period in accordance with legacy IEEE 802.11 communicationtechniques, although this is not a requirement.

In some embodiments, the HE communications during the control period maybe configurable to use one of 20 MHz, 40 MHz, or 80 MHz contiguousbandwidths or an 80+80 MHz (160 MHz) non-contiguous bandwidth. In someembodiments, a 320 MHz channel width may be used. In some embodiments,sub-channel bandwidths less than 20 MHz may also be used. In theseembodiments, each channel or sub-channel of an HE communication may beconfigured for transmitting a number of spatial streams.

In some embodiments, high-efficiency (HE) wireless techniques may beused, although the scope of embodiments is not limited in this respect.As an example, techniques included in 802.11ax standards and/or otherstandards may be used. In accordance with some embodiments, a masterstation 102 and/or HE stations 104 may generate an HE packet inaccordance with a short preamble format or a long preamble format. TheHE packet may comprise a legacy signal field (L-SIG) followed by one ormore HE signal fields (HE-SIG) and an HE long-training field (HE-LTF).For the short preamble format, the fields may be configured forshorter-delay spread channels. For the long preamble format, the fieldsmay be configured for longer-delay spread channels. These embodimentsare described in more detail below. It should be noted that the terms“HEW” and “HE” may be used interchangeably and both terms may refer tohigh-efficiency Wireless Local Area Network operation and/orhigh-efficiency Wi-Fi operation.

As used herein, the term “circuitry” may refer to, be part of, orinclude an Application Specific Integrated Circuit (ASIC), an electroniccircuit, a processor (shared, dedicated, or group), and/or memory(shared, dedicated, or group) that execute one or more software orfirmware programs, a combinational logic circuit, and/or other suitablehardware components that provide the described functionality. In someembodiments, the circuitry may be implemented in, or functionsassociated with the circuitry may be implemented by, one or moresoftware or firmware modules. In some embodiments, circuitry may includelogic, at least partially operable in hardware. Embodiments describedherein may be implemented into a system using any suitably configuredhardware and/or software.

FIG. 2 illustrates a block diagram of an example machine in accordancewith some embodiments. The machine 200 is an example machine upon whichany one or more of the techniques and/or methodologies discussed hereinmay be performed. In alternative embodiments, the machine 200 mayoperate as a standalone device or may be connected (e.g., networked) toother machines. In a networked deployment, the machine 200 may operatein the capacity of a server machine, a client machine, or both inserver-client network environments. In an example, the machine 200 mayact as a peer machine in peer-to-peer (P2P) (or other distributed)network environment. The machine 200 may be an AP 102, STA 103, HEdevice, HE AP, HE STA, UE, eNB, mobile device, base station, personalcomputer (PC), a tablet PC, a set-top box (STB), a personal digitalassistant (PDA), a mobile telephone, a smart phone, a web appliance, anetwork router, switch or bridge, or any machine capable of executinginstructions (sequential or otherwise) that specify actions to be takenby that machine. Further, while only a single machine is illustrated,the term “machine” shall also be taken to include any collection ofmachines that individually or jointly execute a set (or multiple sets)of instructions to perform any one or more of the methodologiesdiscussed herein, such as cloud computing, software as a service (SaaS),other computer cluster configurations.

Examples as described herein, may include, or may operate on ogic or anumber of components, modules, or mechanisms. Modules are tangibleentities (e.g., hardware) capable of performing specified operations andmay be configured or arranged in a certain manner. In an example,circuits may be arranged (e.g., internally or with respect to externalentities such as other circuits) in a specified manner as a module. Inan example, the whole or part of one or more computer systems (e.g., astandalone, client or server computer system) or one or more hardwareprocessors may be configured by firmware or software (e.g.,instructions, an application portion, or an application) as a modulethat operates to perform specified operations. In an example, thesoftware may reside on a machine readable medium. In an example, thesoftware, when executed by the underlying hardware of the module, causesthe hardware to perform the specified operations.

Accordingly, the term “module” is understood to encompass a tangibleentity, be that an entity that is physically constnicted, specificallyconfigured (e.g., hardwired), or temporarily (e.g., transitorily)configured (e.g., programmed) to operate in a specified manner or toperform part or all of any operation described herein. Consideringexamples in which modules are temporarily configured, each of themodules need not be instantiated at any one moment in time. For example,where the modules comprise a general-purpose hardware processorconfigured using software, the general-purpose hardware processor may beconfigured as respective different modules at different times. Softwaremay accordingly configure a hardware processor, for example, toconstitute a particular module at one instance of time and to constitutea different module at a different instance of time.

The machine (e.g., computer system) 200 may include a hardware processor202 (e.g., a central processing unit (CPU), a graphics processing unit(CPU), a hardware processor core, or any combination thereof), a mainmemory 204 and a static memory 206, some or all of which may communicatewith each other via an interlink (e.g., bus) 208. The machine 200 mayfurther include a display unit 210, an alphanumeric input device 212(e.g., a keyboard), and a user interface (UT) navigation device 214(e.g., a mouse). In an example, the display unit 210, input device 212and UI navigation device 214 may be a touch screen display. The machine200 may additionally include a storage device (e.g., drive unit) 216, asignal generation device 218 (e.g., a speaker), a network interfacedevice 220, and one or more sensors 221, such as a global positioningsystem (GPS) sensor, compass, accelerometer, or other sensor. Themachine 200 may include an output controller 228, such as a serial(e.g., universal serial bus (USB), parallel, or other wired or wireless(e.g., infrared (IR), near field communication (NFC), etc.) connectionto communicate or control one or more peripheral devices (e.g., aprinter, card reader, etc.).

The storage device 216 may include a machine readable medium 222 onwhich is stored one or more sets of data structures or instructions 224(e.g., software) embodying or utilized by any one or more of thetechniques or functions described herein. The instructions 224 may alsoreside, completely or at least partially, within the main memory 204,within static memory 206, or within the hardware processor 202 duringexecution thereof by the machine 200. In an example, one or anycombination of the hardware processor 202, the main memory 204, thestatic memory 206, or the storage device 216 may constitute machinereadable media. In sonic embodiments, the machine readable medium may beor may include a non-transitory computer-readable storage medium. Insome embodiments, the machine readable medium may be or may include acomputer-readable storage medium.

While the machine readable medium 222 is illustrated as a single medium,the term “machine readable medium” may include a single medium ormultiple media (e.g., a centralized or distributed database, and/orassociated caches and servers) configured to store the one or moreinstructions 224. The term “machine readable medium” may include anymedium that is capable of storing, encoding, or carrying instructionsfor execution by the machine 200 and that cause the machine 200 toperform any one or more of the techniques of the present disclosure, orthat is capable of storing, encoding or carrying data structures used byor associated with such instructions. Non-limiting machine readablemedium examples may include solid-state memories, and optical andmagnetic media. Specific examples of machine readable media may include:non-volatile memory, such as semiconductor memory devices (e.g.,Electrically Programmable Read-Only Memory (EPROM), ElectricallyErasable Programmable Read-Only Memory (EEPROM)) and flash memorydevices; magnetic disks, such as internal hard disks and removabledisks; magneto-optical disks; Random Access Memory (RAM); and CD-ROM andDVD-ROM disks. In some examples, machine readable media may includenon-transitory machine readable media. In some examples, machinereadable media may include machine readable media that is not atransitory propagating signal.

The instructions 224 may further be transmitted or received over acommunications network 226 using a transmission medium via the networkinterface device 220 utilizing any one of a number of transfer protocols(e.g., frame relay, internee protocol (IP), transmission controlprotocol (TCP), user datagram protocol (UDP), hypertext transferprotocol (HTTP), etc.). Example communication networks may include alocal area network (LAN), a wide area network (WAN), a packet datanetwork (e.g., the Internet), mobile telephone networks (e.g., cellularnetworks), Plain Old Telephone (POTS) networks, and wireless datanetworks (e.g., Institute of Electrical and Electronics Engineers (IEEE)802.11 family of standards known as Wi-Fi®, IEEE 802.16 family ofstandards known as WiMax®), IEEE 802.15.4 family of standards, a LongTerm Evolution (LTE) family of standards, a Universal MobileTelecommunications System (UMTS) family of standards, peer-to-peer (P2P)networks, among others. In an example, the network interface device 220may include one or more physical jacks (e.g., Ethernet, coaxial, orphone jacks) or one or more antennas to connect to the communicationsnetwork 226. In an example, the network interface device 220 may includea plurality of antennas to wirelessly communicate using at least one ofsingle-input multiple-output (SIMO), multiple-input multiple-output(MIMO), or multiple-input single-output (MISO) techniques. In someexamples, the network interface device 220 may wirelessly communicateusing Multiple User MIMO techniques. The term “transmission medium”shall be taken to include any intangible medium that is capable ofstoring, encoding or carrying instructions for execution by the machine200, and includes digital or analog communications signals or otherintangible medium to facilitate communication of such software.

FIG. 3 illustrates a station (STA) in accordance with some embodimentsand an access point (AP) in accordance with some embodiments. It shouldbe noted that in some embodiments, an STA or other mobile device mayinclude some or all of the components shown in either FIG. 2 or FIG. 3(as in 300) or both. The STA 300 may be suitable for use as an STA 103as depicted in FIG. 1, in some embodiments. It should also be noted thatin some embodiments, an AP or other base station may include some or allof the components shown in either FIG. 2 or FIG. 3 (as in 350) or both.The AP 350 may be suitable for use as an AP 102 as depicted in FIG. 1,in some embodiments.

The STA 300 may include physical layer circuitry 302 and a transceiver305, one or both of which may enable transmission and reception ofsignals to and from components such as the AP 102 (FIG. 1), other STA.sor other devices using one or more antennas 301. As an example, thephysical layer circuitry 302 may perform various encoding and decodingfunctions that may include formation of baseband signals fortransmission and decoding of received signals. As another example, thetransceiver 305 may perform various transmission and reception functionssuch as conversion of signals between a baseband range and a RadioFrequency (RF) range. Accordingly, the physical layer circuitry 302 andthe transceiver 305 may be separate components or may be part of acombined component. In addition, some of the described functionalityrelated to transmission and reception of signals may be performed by acombination that may include one, any or all of the physical layercircuitry 302, the transceiver 305, and other components or layers. TheSTA 300 may also include medium access control layer (MAC) circuitry 304for controlling access to the wireless medium. The STA 300 may alsoinclude processing circuitry 306 and memory 308 arranged to perform theoperations described herein.

The AP 350 may include physical layer circuitry 352 and a transceiver355, one or both of which may enable transmission and reception ofsignals to and from components such as the STA 103 (FIG. 1), other APsor other devices using one or more antennas 351. As an example, thephysical layer circuitry 352 may perform various encoding and decodingfunctions that may include formation of baseband signals fortransmission and decoding of received signals. As another example, thetransceiver 355 may perform various transmission and reception functionssuch as conversion of signals between a baseband range and a RadioFrequency (RF) range. Accordingly, the physical layer circuitry 352 andthe transceiver 355 may be separate components or may be part of acombined component. In addition, some of the described functionalityrelated to transmission and reception of signals may be performed by acombination that may include one, any or all of the physical layercircuitry 352, the transceiver 355, and other components or layers. TheAP 350 may also include medium access control layer (MAC) circuitry 354for controlling access to the wireless medium. The AP 350 may alsoinclude processing circuitry 356 and memory 358 arranged to perform theoperations described herein.

The antennas 301, 351, 230 may comprise one or more directional oromnidirectional antennas, including, for example, dipole antennas,monopole antennas, patch antennas, loop antennas, microstrip antennas orother types of antennas suitable for transmission of RF signals. In somemultiple-input multiple-output (MIMO)) embodiments, the antennas 301,351, 230 may be effectively separated to take advantage of spatialdiversity and the different channel characteristics that may result.

In some embodiments, the STA 300 may be configured as an HE device 104(FIG. 1), and may communicate using OFDM and/or OFDMA communicationsignals over a multicarrier communication channel. In some embodiments,the AP 350 may be configured to communicate using OFDM and/or OFDMAcommunication signals over a multicarrier communication channel. In someembodiments, the HE device 104 may be configured to communicate usingOFDM communication signals over a multicarrier communication channel.Accordingly, in some cases, the STA 300, AP 350 and/or HE device 104 maybe configured to receive signals in accordance with specificcommunication standards, such as the Institute of Electrical andElectronics Engineers (IEEE) standards including IEEE 802.11-2012,802.11n-2009 and/or 802.11ac-2013 standards and/or proposedspecifications for WLANs including proposed HE standards, although thescope of the embodiments is not limited in this respect as they may alsohe suitable to transmit and/or receive communications in accordance withother techniques and standards. In some other embodiments, the AP 350,HE device 104 and/or the STA 300 configured as an HE device 104 may beconfigured to receive signals that were transmitted using one or moreother modulation techniques such as spread spectrum modulation (e.g.,direct sequence code division multiple access (DS-CDMA) and/or frequencyhopping code division multiple access (FH-CDMA)), time-divisionmultiplexing (TDM) modulation, and/or frequency-division multiplexing(FDM) modulation, although the scope of the embodiments is not limitedin this respect. Embodiments disclosed herein provide two preambleformats for High Efficiency (HE) Wireless LAN standards specificationthat is under development in the IEEE Task Group 11ax (TGax).

In some embodiments, the STA 300 and/or AP 350 may be a mobile deviceand may be a portable wireless communication device, such as a personaldigital assistant (PDA), a laptop or portable computer with wirelesscommunication capability, a web tablet, a wireless telephone, asmartphone, a wireless headset, a pager, an instant messaging device, adigital camera, an access point, a television, a wearable device such asa medical device (e.g., a heart rate monitor, a blood pressure monitor,etc.), or other device that may receive and/or transmit informationwirelessly. In some embodiments, the STA 300 and/or AP 350 may beconfigured to operate in accordance with 802.11 standards, although thescope of the embodiments is not limited in this respect. Mobile devicesor other devices in some embodiments may be configured to operateaccording to other protocols or standards, including other IEEEstandards, Third Generation Partnership Project (3GPP) standards orother standards. In some embodiments, the STA 300 and/or AP 350 mayinclude one or more of a keyboard, a display, a non-volatile memoryport, multiple antennas, a graphics processor, an application processor,speakers, and other mobile device elements. The display may be an LCDscreen including a touch screen.

Although the STA 300 and the AP 350 are each illustrated as havingseveral separate functional elements, one or more of the functionalelements may be combined and may be implemented by combinations ofsoftware-configured elements, such as processing elements includingdigital signal processors (DSPs), and/or other hardware elements. Forexample, some elements may comprise one or more microprocessors, DSPs,field-programmable gate arrays (FPGAs), application specific integratedcircuits (ASICs), radio-frequency integrated circuits (RFICs) andcombinations of various hardware and logic circuitry for performing atleast the functions described herein. In some embodiments, thefunctional elements may refer to one or more processes operating on oneor more processing elements.

Embodiments may be implemented in one or a combination of hardware,firmware and software. Embodiments may also be implemented asinstructions stored on a computer-readable storage device, which may beread and executed by at least one processor to perform the operationsdescribed herein. A computer-readable storage device may include anynon-transitory mechanism for storing information in a form readable by amachine (e.g., a computer). For example, a computer-readable storagedevice may include read-only memory (ROM), random-access memory (RAM),magnetic disk storage media, optical storage media, flash-memorydevices, and other storage devices and media. Some embodiments mayinclude one or more processors and may be configured with instructionsstored on a computer-readable storage device.

It should be noted that in some embodiments, an apparatus used by theSTA 300 may include various components of the STA 300 as shown in FIG. 3and/or the example machine 200 as shown in FIG. 2. Accordingly,techniques and operations described herein that refer to the STA 300 (or103) may be applicable to an apparatus for an STA, in some embodiments.It should also be noted that in some embodiments, an apparatus used bythe AP 350 may include various components of the AP 350 as shown in FIG.3 and/or the example machine 200 as shown in FIG. 2 Accordingly,techniques and operations described herein that refer to the AP 350 (or102) may be applicable to an apparatus for an AP, in some embodiments.In addition, an apparatus for a mobile device and/or base station mayinclude one or more components shown in FIGS. 2-3, in some embodiments.Accordingly, techniques and operations described herein that refer to amobile device and/or base station may be applicable to an apparatus fora mobile device and/or base station, in some embodiments.

In accordance with some embodiments, the AP 102 may transmit a highefficiency (HE) physical layer convergence procedure (PLCP) protocoldata unit (PPDU) that may include a legacy long training field (L-LTF),a legacy signal (L-SIG) field, and an HE signal (HE-SIG) field. TheHE-SIG may be based on HE-SIG symbols mapped to a group of HEsubcarriers that includes legacy subcarriers and HE extensionsubcarriers. The L-LTF may be based on L-LTF pilot symbols mapped to thelegacy subcarriers. The L-SIG may be based on L-SIG legacy symbolsmapped to the legacy subcarriers and L-SIG extension pilot symbolsmapped to the HE extension subcarriers. The AP 102 may scale aper-subcarrier power of the L-SIG extension pilot symbols to match aper-subcarrier power of the L-LTF pilot symbols. These embodiments willbe described in more detail below.

FIG. 4 illustrates the operation of a method of communication inaccordance with some embodiments. It is important to note thatembodiments of the method 400 may include additional or even feweroperations or processes in comparison to what is illustrated in FIG. 4.In addition, embodiments of the method 400 are not necessarily limitedto the chronological order that is shown in FIG. 4. In describing themethod 400, reference may be made to FIGS. 1-3 and 5-6, although it isunderstood that the method 400 may be practiced with any other suitablesystems, interfaces and components.

In some embodiments, the STA 103 may be configurable to operate as an HEdevice 104. Although reference may be made to an STA 103 herein,including as part of the descriptions of the method 400 and/or othermethods described herein, it is understood that an HE device 104 and/orSTA 103 configurable to operate as an HE device 104 may be used in someembodiments, In addition, the method 400 and other methods describedherein may refer to STAs 103, HE devices 104 and/or APs 102 operating inaccordance with one or more standards and/or protocols, such as 802.11,wireless local area network (WLAN) and/or other, but embodiments ofthose methods are not limited to just those devices. In someembodiments, the method 400 and other methods described herein may bepracticed by other mobile devices, such as an Evolved Node-B (eNB) orUser Equipment (UE). The method 400 and other methods described hereinmay also be practiced by wireless devices configured to operate in othersuitable types of wireless communication systems, including systemsconfigured to operate according to various Third Generation PartnershipProject (3GPP) Long Term Evolution (LTE) standards. The method 400 mayalso be applicable to an apparatus for an STA 103, HE device 104 and/orAP 102 or other device described above, in some embodiments.

It should also be noted that embodiments are not limited by referencesherein (such as in descriptions of the methods 400, 600 and/or otherdescriptions herein) to transmission, reception and/or exchanging ofelements such as frames, messages, requests, indicators, signals orother elements. In some embodiments, such an element may be generated,encoded or otherwise processed by processing circuitry (such as by abaseband processor included in the processing circuitry) fortransmission. The transmission may be performed by a transceiver orother component, in some cases. In some embodiments, such an element maybe decoded, detected or otherwise processed by the processing circuitry(such as by the baseband processor). The element may be received by atransceiver or other component, in some cases. in some embodiments, theprocessing circuitry and the transceiver may be included in a sameapparatus. The scope of embodiments is not limited in this respect,however, as the transceiver may be separate from the apparatus thatcomprises the processing circuitry, in some embodiments.

At operation 405 of the method 400, the AP 102. may contend for accessto a wireless medium. In some embodiments, the AP 102 may contend forthe wireless medium during a contention period to receive exclusivecontrol of the medium during a period, including but not limited to anHE control period. The AP 102 may transmit a frame and/or message, suchas an HE PPDU to be described below, during the HE control period, insome embodiments. It should be noted, however, that embodiments are notlimited to transmission during an HE control period or transmission inaccordance with the exclusive control of the medium. Accordingly, the HEPPDU and/or other frame may be transmitted in contention-based scenariosand/or other scenarios, in some cases.

At operation 410, the AP 102 may scale pilot subcarriers, datasubcarriers and/or other subcarriers of an HE PPDU that is to betransmitted to one or more STAs 103. At operation 415, the AP 102 maytransmit the HE PPDU to the one or more STAs 103. In some embodiments,the HE PPDU may be transmitted in accordance with orthogonal frequencydivision multiple access (OFDMA) techniques and/or orthogonal frequencydivision multiplexing (OFDM) techniques. The scope of embodiments is notlimited in this respect, however, as other techniques may be used,including but not limited to single carrier frequency division multipleaccess (SC-FDMA) signals and/or other techniques.

It should be noted that HE PPDUs, such as high efficiency (HE) physicallayer convergence procedure (PLCP) protocol data unit (PPDU) and/orothers, may be exchanged between the AP 102 and one or more STAs 103, insome embodiments. The scope of embodiments is not limited in thisrespect, however, as the fields described for the HE PPDUs may beexchanged using other frames and/or other types of frames, in someembodiments.

In some embodiments, an HE PPDU may include one or more of a legacyshort training field (L-STF), legacy long training field (L-LTF), legacysignal field (L-SIG), repeated L-SIG (RL-SIG), HE signal field (such asHE-SIG-A and/or HE-SIG-B), one or more HE data fields and/or otherfields. As an example, the HE PPDU may include an L-STF, L-LTF, L-SIG,RL-SIG, HE-SIG-A, HE-SIG-B, and one or more HE data fields. It shouldalso be noted that references herein to transmission of the HE PPDUand/or one or more fields of the HE PPDU are not limiting. In someembodiments, the HE PPDU may be generated for transmission by the AP 102to one or more STAs 103. In some embodiments, one or more fields (suchas an L-STF, L-L-LTF, L-SIG, RL-SIG, HE-SIG-A, HE-SIG-B, one or more HEdata fields and/or one or more other fields) may be encoded by the AP102 and may be included in the HE PPDU 500.

In some embodiments, the L-STF may be based on L-STF pilot symbols,which may enable channel estimation and/or channel tracking by one ormore STAs 103. In some embodiments, the L-LTF may be based on L-LTFpilot symbols, which may enable channel estimation and/or channeltracking by one or more STAs 103. In some embodiments, the L-SIG may bebased on L-SIG legacy symbols, which may include data symbols, pilotsymbol(s) or a combination thereof. As a non-limiting example, 52 L-SIGlegacy symbols may include 48 L-SIG legacy data symbols and 4 L-SIGlegacy pilot symbols. The L-SIG may also be based on L-SIG extensionpilot symbols, in some cases. For instance, as will be described below,four L-SIG extension pilot symbols may be used. The L-SIG legacy datasymbols may be used to indicate information related to reception inaccordance with legacy techniques, in some cases. The L-SIG legacy pilotsymbols may be used to enable channel estimation and/or channel trackingby one or more STAs 103, such as in a portion of the legacy subcarriers,in some cases. The L-SIG extension pilot symbols may be used to enablechannel estimation and/or channel tracking by one or more STAs 103, suchas in the HE extension subcarriers, in some cases. As a non-limitingexample, the L-SIG extension pilot symbols may enable a determination,by one or more STAs 103, of an extended channel estimate of both thelegacy subcarriers and the HE extension subcarriers in comparison to alegacy channel estimate of the legacy subcarriers based on the L-LTFpilot symbols, in some cases. In some embodiments, the RL-SIG may be arepetition of the L-SIG, although the scope of embodiments is notlimited in this respect. The RL-SIG may be of a same structure orsimilar structure as the in some embodiments. For instance, the RL-SIGmay be the same or similar to the L-SIG in terms of number, type,arrangement, power scaling and/or other aspects of pilot symbols,extension pilot symbols, data symbols, subcarriers and/or otherelements, in some embodiments.

In some embodiments, the HE-SIG, HE-SIG-A and/or HE-SIG-B may be basedon HE-SIG pilot symbols and/or HE-SIG data symbols. The HE-SIG pilotsymbols may enable channel estimation and/or channel tracking by one ormore STAs 103, in some embodiments. Other operations related todecoding, demodulation, synchronization and/or other may be enabled, insome cases. The HE-SIG data symbols may be used, in some embodiments, tocommunicate data and/or control information. For instance, controlinformation related to reception of HE data fields may be communicatedby the HE-SIG data symbols

It should be noted that these examples of operations that may be enabledby symbols of the L-STF, L-LTF, L-SIG, RL-SIG, HE-SIG, HE-SIG-A and/orHE-SIG-B are not limiting, as other operations, such as operationsrelated to decoding, demodulation, synchronization and/or other, mayalso be enabled by those symbols. In addition, the symbols maycommunicate control information and/or data, in some embodiments.

In some embodiments, symbol periods (such as OFDM symbol periods) may beallocated for the above fields. For instance, the L-STF may betransmitted in an L-STF symbol period of the HE PPDU, the L-LTF may betransmitted in an L-LTF symbol period of the HE PPDU, the L-SIG may betransmitted in an L-SIG symbol period of the HE PPDU, the HE-SIG may betransmitted in an HE-SIG symbol period of the HE PPDU, the HE-SIG-A maybe transmitted in an HE-SIG-A symbol period of the HE PPDU, the HE-SIG-Bmay be transmitted in an HE-SIG-B symbol period of the HE PPDU, and/oran HE data field may be transmitted in a group of one or more HE datasymbol periods of the HE PPDU.

In some embodiments, a group of legacy subcarriers may be used fortransmission of one or more fields of the HE PPDU, In addition, one ormore fields may be transmitted in a group of HE subcarriers that mayinclude the legacy subcarriers and may further include a group of HEextension subcarriers. Accordingly, channel resources used for legacycommunication (the legacy subcarriers) may be extended for HEcommunication. A group of HE subcarriers used for HE communication mayinclude the legacy subcarriers and may also include a group of HEextension subcarriers.

In some embodiments, the L-LTF may be based on L-LTF pilot symbolsmapped to the group of legacy subcarriers in an L-LTF symbol of the HEPPDU. In some embodiments, the L-SIG may be based on L-SIG legacysymbols mapped to the legacy subcarriers in an L-SIG symbol of the HEPPDU. It should be noted that the L-SIG legacy symbols may include L-SIGlegacy data symbols, L-SIG legacy pilot symbols or a combinationthereof, in some cases. The L-SIG may be further based on L-SIGextension pilot symbols mapped to the HE extension subcarriers in theL-SIG symbol of the HE PPDU. A per-subcarrier power of the L-SIGextension pilot symbols may be scaled to match a per-subcarrier power ofthe L-LTF pilot symbols. It should be noted that similar techniques maybe used for an RL-SIG, if present in the HE PPDU.

In some embodiments, the HE-SIG may be based on HE-SIG symbols mapped tothe group of HE subcarriers (which may include the legacy subcarriersand the group of HE extension subcarriers).

As a non-limiting example, channel resources may include a number ofsubcarriers of predetermined bandwidth of 312.5 kHz. Accordingly,channel resources of 20 MHz may include 64 sub-carriers allocated asguard-bands, used subcarriers, DC subcarrier(s), data subcarriers, pilotsubcarriers and/or other subcarriers. The group of legacy subcarriersmay include 52 subcarriers, the group of HE extension subcarriers mayinclude 4 subcarriers, and the group of HE subcarriers may include 56subcarriers.

In symbol periods in which a configuration for the legacy sub-carriersis used, the channel resources may include a lower guard band at a loweredge of the channel resources, followed by 26 legacy subcarriers,followed by a DC subcarrier, followed by 26 legacy subcarriers, followedby an upper guard band at an upper edge of the channel resources. Insymbol periods in which a configuration for the HE sub-carriers is used,the channel resources may include a lower guard band at a lower edge ofthe channel resources, followed by two HE extension subcarriers,followed by 26 legacy subcarriers, followed by a DC subcarrier, followedby 26 legacy subcarriers, followed by two HE extension subcarriers,followed by an upper guard band at an upper edge of the channelresources. Accordingly, a portion of each guard band of the legacyconfiguration may be used for the HE extension subcarriers of the HEconfiguration, in some cases.

The HE PPDU may not necessarily include all of the fields describedabove, in some embodiments. In some cases, the fields may appear in thechronological order described above, but embodiments are not limited assuch. In addition, the HE PPDU may include more than one of any of thefields described above, in some embodiments.

The pilot symbols and/or data symbols may be scaled in some embodiments.Different scaling techniques may be used. As an example, aper-subcarrier power of the L-SIG extension pilot symbols may be scaledto match a per-subcarrier power of the L-LTF pilot symbols. Accordingly,pilot symbols for the legacy subcarriers and the HE extensionsubcarriers may be transmitted as a same per-subcarrier power, in thisexample.

Continuing the example, the L-LTF pilot symbols may be scaled for equalper-subcarrier power, in some cases. Accordingly, when 52 legacysubcarriers are used, each L-LTF pilot symbol may be scaled by a factorof 1/52 with respect to a total power of the L-LTF symbol period. Forinstance, each L-LTF pilot symbol may be scaled for a power of P*(1/52)when a target total power (and/or normalized power restriction) of theL-LTF symbol period is P. When the L-SIG extension pilot symbols arescaled to match the per-subcarrier power of the L-LTF pilot symbols,each L-SIG extension pilot symbol may be scaled for a power of P*(1/52).

Continuing the example, a per-subcarrier power of the L-SIG legacysymbols may also be scaled based on various criteria. In someembodiments, a. normalized power restriction for the L-SIG symbol periodmay be used, and the L-SIG legacy symbols may be scaled (along with thescaling of the L-SIG extension pilot symbols) in accordance with thepower restriction. As an example, when the L-SIG symbol period and theL-LTF symbol period are to be normalized to the same total power (suchas P), the per-subcarrier power of the L-SIG legacy symbols may bescaled by a product of (1/52) and (48/52) with respect to the totalpower of the L-SIG symbol period. That is, a scaling factor of (48/2704)may be used. In addition, the per-subcarrier power of the L-SIGextension pilot symbols may be scaled by a factor of (1/52) with respectto the total power of the L-SIG symbol period. It should be noted that,in this case, the L-SIG extension pilot symbols may be boosted, withrespect to the L-SIG legacy symbols, by a factor of 52/48(0.347 dB) tomatch the per-subcarrier power of the L-LTF pilot symbols.

The above example, in which the L-LTF symbols and the L-SIG symbols arescaled for the same total power for the L-LTF symbol period and theL-SIG symbol period, may be applicable to a normal mode of operation, anon-extended coverage mode, a normal HE PPDU and/or non-extendedcoverage HE PPDU. As another example, for an extended coverage mode(and/or extended coverage HE PPDU), the total power of the L-LTF symbolperiod may be twice that of the L-SIG symbol period (3.01 dB higher).Embodiments are not limited to the particular ratio of two (3.01 dB)between the total powers of the L-LTF symbol period and the L-SIG symbolperiod, however, as any suitable ratio may be used.

In the extended coverage case described above, various subcarrierscaling operations will be described below using total powers of P and2P for the L-SIG symbol period and the L-LTF symbol period,respectively. Each L-LTF pilot symbol may be scaled for a power of2P*(1/52) when a target total power (and/or normalized powerrestriction) of the L-LTF symbol period is 2P. When the L-SIG extensionpilot symbols are scaled to match the per-subcarrier power of the L-LTFpilot symbols, each L-SIG extension pilot symbol may be scaled for apower of 2P*(1/52). In addition, the L-SIG legacy symbols may be scaledfor a power of P*(1/52)*(44/52). That is, a scaling factor of (44/2704)may be used. Accordingly, the L-SIG extension pilot symbols may bescaled (by a factor of (2/52) with respect to the total power of theL-SIG symbol period) to match the per-subcarrier power of the L-LTFsymbol period. The per-subcarrier power of the L-SIG legacy symbols maybe scaled by a product of (1/52) and (44/52) with respect to the totalpower of the L-SIG symbol period. That is, a scaling factor of (44/2704)may be used. It should be noted that the L-SIG extension pilot symbolsmay be boosted, with respect to the L-SIG legacy symbols, by a factor of52/22(0.347 dB) to match the per-subcarrier power of the L-LTF pilotsymbols.

As another example, a per-subcarrier power of the HE-SIG symbols may hescaled to match the per-subcarrier power of the L-LTF pilot symbols andthe per-subcarrier power of the L-SIG extension pilot symbols.

As another example, when the HE PPDU is generated for an extendedcoverage mode, the target symbol power of a legacy short training field(L-STF) and/or L-LTF may be boosted by 3 dB (or any suitable scaling indB or scalar scaling) relative to a target symbol power of the HE-SIG(such as HE-SIG-A and/or other). The extra four tones of the L-SIGand/or RL-SIG on the edge of the channel resources (in a 20 MHz band orotherwise) may be scaled to have the same per-tone transmission power asthe per-tone transmission power of L-LTF tones. In addition, otherpopulated tones in the L-SIG and/or RL-SIG (such as legacy tones and/orother) may be scaled to have a 3 dB (or any suitable scaling in dB orscalar scaling) lower per-tone transmission power than the per-tonetransmission power of the L-LTF tones.

At operation 420, the AP 102 may receive an uplink HE PPDU from an STA103. The AP 102 may determine channel estimates based on the uplink HEPPDU at operation 425. At operation 430, the AP 102 may decode one ormore HE data fields of the uplink HE PPDU. In some embodiments, some orall of the concepts and/or techniques described herein regarding thetransmission of the HE PPDU by the AP 102 may be applicable to an uplinkHE PPDU transmitted by an STA 103 and received by the AP 102. Forinstance, concepts such as scaling operations, legacy subcarriers, HEsubcartiers, HE extension subcarriers, data symbol, pilot symbols,extension pilot symbols and/or others described for the HE PPDUtransmitted by the AP 102 may be applicable to the uplink HE PPDU, insome cases.

FIG. 5 illustrate example frames that may be exchanged in accordancewith some embodiments. It should be noted that the examples 500, 550shown in FIG. 5 may illustrate some or all of the concepts andtechniques described herein in some cases, but embodiments are notlimited by the examples 500, 550. For instance, embodiments are notlimited by the name, number, type, size, ordering, arrangement and/orother aspects of the frames, signals, fields, data blocks, controlheaders, tones, subcarriers, channel resources and other elements asshown in FIG. 5. Although some of the elements shown in the examples ofFIG. 5 may be included in an 802.11 standard and/or other standard,embodiments are not limited to usage of such elements that are includedin standards.

The example HE PPDUs 500 and/or 550 illustrated in FIG. 5 may betransmitted by the AP 102 to one or more STAs 103. In some embodiments,the HE PPDUs 500 and/or 550 may be used by STAs 103 for uplinkcommunication with the AP 102. It is understood that, in someembodiments, the HE PPDUs 500 and/or 550 may not necessarily include allof the fields shown in FIG. 5 and may even include additional fields insome cases.

In addition, the HE PPDUs 500 and/or 550 may be generated fortransmission by the AP 102 to one or more STAs 103, in some embodiments.One or more fields described below (and/or others) may be encoded by theAP 102 and may be included in the HE PPDU 500 and/or 550, in someembodiments.

The HE PPDU 500 may include one or more L-LTFs 505 which may betransmitted using 52 tones. The L-LTFs 505 may be based on TF pilotsymbols, in some cases. The HE PPDU 500 may further include an 510,which may be transmitted using 56 tones, which may include 52 tones and4 extra tones 515, The L-SIG 510 may be based on legacy L-SIG symbols,which may include legacy L-SIG pilot symbols and/or legacy L-SIG datasymbols, in some cases. The L-SIG 510 may be further based on extrapilot symbols (such as L-SIG extension pilot symbols), such as in thesymbols mapped to the 4 extra tones 515, The HE PPDU 500 may furtherinclude an RL-SIG 520, which may be of a same or similar format as theL-SIG 510, and may be a repetition of the L-SIG 510 in some cases. TheRL-SIG 520 may be transmitted using 56 tones, which may include 52 tonesand 4 extra tones 525. The RL-SIG 520 may be based on legacy RL-SIGsymbols, which may include legacy RL-SIG pilot symbols and/or legacyRL-SIG data symbols, in some cases. The HE PPDU 500 may further includean HE-SIG-A 530, which may be transmitted using 56 tones. The HE PPDU500 may further include an HE-SIG-B 535, which may be transmitted using56 tones. The HE-SIG-A 530 and/or HE-SIG-B 535 may include controlinformation for one or more data fields 540 (such as HE data fields) ofthe HE PPDU 500, in some cases. The HE PPDU 500 may further include oneor more data fields 540, such as HE data fields, which may betransmitted using 56 tones.

The HE PPDU 550 may include one or more 555 which may be transmittedusing 56 tones. The L-LTFs 555 may be based on L-LTF pilot symbols, insome cases. The HE PPDU 550 may further include an L-SIG 560, which maybe transmitted using 52 tones. The L-SIG 560 may be based on legacyL-SIG symbols, which may include legacy L-SIG pilot symbols and/orlegacy L-SIG data symbols, in some cases. The HE PPDU 550 may furtherinclude an RL-SIG 570, which may be of a same or similar format as theL-SIG 560, and may be a repetition of the L-SIG 560 in some cases. TheRL-SIG 570 may be transmitted using 52 tones. The RL-SIG 570 may bebased on legacy RL-SIG symbols, which may include legacy RL-SIG pilotsymbols and/or legacy RL-SIG data symbols, in some cases. The HE PPDU550 may further include an HE-SIG-A 580, which may be transmitted using56 tones. The HE PPDU 550 may further include an HE-SIG-B 585, which maybe transmitted using 56 tones, The HE-SIG-A 580 and/or HE-SIG-B 585 mayinclude control information for one or more data fields 590 (such as HEdata fields) of the HE PPDU 550, in some cases. The HE PPDU 550 mayfurther include one or more data fields 590, such as HE data fields,which may be transmitted using 56 tones.

It should be noted that in the HE PPDU 500, the 4 extra tones 515, 525are included as part of the L-SIG 510 and. RL-SIG 520, respectively, andare excluded from the L-LTF 505. In the HE PPDU 550, the 4 extra tones557 are included as part of the L-LTF 555 and are excluded from theL-SIG 560 and RL-SIG 570, In some embodiments, scaling techniquesdescribed herein for embodiments in which extra tones (such as L-SIGextension pilot symbols) are included as part of the L-SIG, may be usedand/or may be modified for usage in embodiments in which extra tones areincluded as part of the L-LTF.

It should be noted that some embodiments may not necessarily include alloperations shown in FIG. 4. As an example, some embodiments may includeoperations 405-415 but may exclude operations 420-430, such as whendownlink transmission of HE PPDUs is performed and uplink reception ofHE PPDUs (transmitted by one or more STAs 103) is not performed. Asanother example, some embodiments may exclude operations 405-415 but mayinclude operations 420-430, such as when downlink transmission of HEPPDUs is not performed and uplink reception of HE PPDUs (transmitted byone or more STAs 103) is performed.

It should also be noted that in some cases, frames and/or elements(including but not limited to those in FIG. 5) may be transmitted inaccordance with contention based techniques. In some embodiments, atransmission of a frame and/or element may be performed after detectionof an inactivity period of the channel to be used for the transmission.For instance, it may be determined, based on channel sensing, that thechannel is available, As a non-limiting example, a minimum time durationfor the inactivity period may be based on an inter-frame spacing (IFS),which may be included in an 802.11 standard and/or other standard. Thatis, when inactivity is detected for a time duration that is greater thanor equal to the IFS, the channel may be determined to be available.Embodiments are not limited to usage of the IFS, however, as other timedurations, which may or may not be included in a standard, may be usedin some cases. in addition, back-off techniques may also be used, insome embodiments,

FIG. 6 illustrates the operation of another method of communication inaccordance with some embodiments. As mentioned previously regarding themethod 400, embodiments of the method 600 may include additional or evenfewer operations or processes in comparison to what is illustrated inFIG. 6 and embodiments of the method 600 are not necessarily limited tothe chronological order that is shown in FIG. 6. In describing themethod 600, reference may be made to FIGS. 1-5, although it isunderstood that the method 600 may be practiced with any other suitablesystems, interfaces and components. In addition, embodiments of themethod 600 may be applicable to APs 102, ST As 103, LEs, eNBs or otherwireless or mobile devices. The method 600 may also be applicable to anapparatus for an AP 102, STA 103 and/or other device described above.

It should be noted that the method 600 may be practiced by an STA 103and may include exchanging of elements, such as frames, signals,messages, fields and/or other elements, with an AP 102. Similarly, themethod 400 may be practiced at an AP 102 and may include exchanging ofsuch elements with an STA 103. In some cases, operations and techniquesdescribed as part of the method 400 may be relevant to the method 600.In addition, embodiments of the method 600 may include operationsperformed at the STA 103 that are reciprocal to or similar to otheroperations described herein performed at the AP 102. For instance, anoperation of the method 600 may include reception of a frame from the AP102 by the STA 103 while an operation of the method 400 may includetransmission of the same frame or similar frame by the AP 102.

In addition, previous discussion of various techniques and concepts maybe applicable to the method 600 in some cases, including HE PPDUs,S-LTFs, L-SIGs, RL-SIGs, HE-SIGs, HE-SIG-As, HE-SIG-Bs, HE data frames,legacy subcarriers, HE subcarriers, HE extension subcarriers, extratones, extra pilots, scaling of per-subcarrier powers, scaling of apower of a symbol period, matching of per-subcarrier powers fordifferent symbol periods, boosting of per-subcarrier powers and/orothers. In addition, the examples shown in FIG. 5 may also beapplicable, in some cases, although the scope of embodiments is notlimited in this respect.

At operation 605, the STA 103 may receive an HE PPDU from an AP 102. Insome embodiments, the HE PPDU may be of a format described regarding themethod 400, although the scope of embodiments is not limited in thisrespect. The example HE PPDU formats 500 and/or 550 may be used, in someembodiments, and other frame formats may also be used in some cases.

At operation 610, the STA 103 may determine channel estimates based onthe received HE PPDU. In some embodiments, the STA 103 may determinechannel estimates of a group of HE subcarriers that includes legacysubcarriers and HE extension subcarriers. As an example, the channelestimates of the legacy subcarriers may be based at least partly onL-LTF pilot symbols mapped to the legacy subcarriers during an L-LTFsymbol period of the HE PPDU. In addition, the channel estimates of theHE extension subcarriers may be based at least partly on L-SIG extensionpilot symbols mapped to the HE extension subcarriers during an L-SIGsymbol period of the HE PPDU.

The channel estimates may be determined, in some cases, based on matchedper-subcarrier transmission powers of the L-LTF pilot symbols and theL-SIG extension pilot symbols. That is, the HE PPDU may be transmitted,by the AP 102, in accordance with a format in which powersper-subcarrier of the L-LTF pilot symbols and the L-SIG extension pilotsymbols are matched (and/or scaled to match). Other scaling may beapplicable to the HE PPDU, and the channel estimation may be determinedbased on such scaling. For instance, scaling of data symbols and/orpilot symbols of any symbol period in accordance with a target power forthe symbol period and/or normalization restriction for the symbol periodmay be taken into account as part of the determination of the channelestimates.

At operation 615, the STA 103 may decode an L-SIG of the HE PPDU. Insome embodiments, the STA 103 may decode, in accordance with the channelestimates of the legacy subcarriers, L-SIG legacy symbols mapped to thelegacy subcarriers in an L-SIG symbol period of the HE PPDU. Atoperation 620, the STA 103 may decode an HE-SIG of the HE PPDU. In someembodiments, the STA 103 may decode, in accordance with the channelestimates of the HE subcarriers, HE-SIG symbols mapped to the HEsubcarriers in an HE-SIG symbol period of the HE PPDU. At operation 625,the STA 103 may decode one or more data fields of the HE PPDU. In someembodiments, the STA 103 may decode, in accordance with the channelestimates of the HE subcarriers, one or more HE data fields that may bebased on HE data symbols and/or HE pilot symbols mapped to the HEsubcarriers in one or more symbol periods of the HE PPDU. For instance,one or more HE data symbol periods may be included in the HE PPM afterthe HE-SIG symbol period(s).

At operation 630 of the method 600, the STA 103 may contend for accessto a wireless medium. At operation 635, the STA 103 may scale pilotsubcarriers, data subcarriers and/or other subcarriers of an uplink HEPPDU that is to be transmitted to the AP 102. At operation 640, the STA103 may transmit the uplink HE PPDU to the AP 102. Techniques forscaling described herein and/or HE PPDU formats described herein may beused, in some embodiments, for the uplink HE PPDU.

In Example 1, an apparatus of an access point (AP) may comprise memory.The apparatus may further comprise processing circuitry. The processingcircuitry may be configured to encode, for transmission, a legacy longtraining field (L-LTF) based on L-LTF pilot symbols mapped to a group oflegacy subcarriers. The processing circuitry may be further configuredto scale a per-subcarrier power for a group of legacy signal (L-SIG)extension pilot symbols to match a per-subcarrier power of the L-LTFpilot symbols. The processing circuitry may be further configured toencode, for transmission, an L-SIG field based on L-SIG legacy symbolsmapped to the legacy subcarriers and further based on the scaled L-SIGextension pilot symbols mapped to a group of high efficiency (HE)extension subcarriers. The processing circuitry may be furtherconfigured to encode, for transmission, an HE signal field (HE-SIG)based on HE-SIG symbols mapped to a group of HE subcarriers thatincludes the legacy subcarriers and the HE extension subcarriers. Theprocessing circuitry may be further configured to generate, fortransmission, an HE physical layer convergence procedure (PLCP) protocoldata unit (PPDU) to include the L-LTF, the L-SIG, and the HE-SIG.

In Example 2, the subject matter of Example 1, wherein the extensionpilot symbols may enable a determination of an extended channel estimateof both the legacy subcarriers and the HE extension subcarriers incomparison to a legacy channel estimate of the legacy subcarriers basedon the L-LTF pilot symbols.

In Example 3, the subject matter of one or any combination of Examples1-2, wherein the processing circuitry may be further configured togenerate the HE PPDU for transmission in channel resources of 20 MHz.The channel resources may include 64 subcarriers of 312.5 kHz. Thechannel resources may include a lower guard band at a lower edge of thechannel resources, followed by two HE extension subcarriers, followed by26 legacy subcarriers, followed by a DC subcarrier, followed by 26legacy subcarriers, followed by two HE extension subcarriers, followedby an upper guard band at an upper edge of the channel resources.

In Example 4, the subject matter of one or any combination of Examples1-3, wherein the processing circuitry may be further configured to boostthe per-subcarrier power of the L-SIG extension pilot symbols, withrespect to a per-subcarrier power of the L-SIG legacy symbols, to matchthe per-subcarrier power of the L-LTF pilot symbols,

In Example 5, the subject matter of one or any combination of Examples1-4, wherein the L-SIG may be encoded for transmission during an L-SIGsymbol period of the HE PPDU. The processing circuitry may be furtherconfigured to scale the per-subcarrier power of the L-SIG legacy symbolsbased on the per-subcarrier power of the L-SIG extension pilot symbolsand a normalized power restriction for the L-SIG symbol period.

In Example 6, the subject matter of one or any combination of Examples1-5, wherein the L-LTF may be encoded for transmission during an L-LTFsymbol period of the HE PPDU, The L-SIG may be encoded for transmissionduring an L-SIG symbol period of the HE PPDU that follows the L-LTFsymbol period. The processing circuitry may be further configured toscale the per-subcarrier power of the L-LTF pilot symbols in accordancewith a target symbol power for the L-LTF symbol period. The processingcircuitry may be further configured to scale the per-subcarrier power ofthe L-SIG extension pilot symbols and the per-subcarrier power of theL-SIG legacy symbols in accordance with a target symbol power for theL-SIG symbol period.

In Example 7, the subject matter of one or any combination of Examples1-6, wherein the HE subcarriers may be of a predetermined bandwidth of312.5 kHz and may be included in channel resources of 20 MHz. The groupof legacy subcarriers may include 52 subcarriers and the group of HEextension subcarriers may include four subcarriers. The L-SIG may bebased on 52 legacy symbols and four L-SIG extension pilot symbols. TheL-LTF may be based on 52 L-LTF pilot symbols.

In Example 8, the subject matter of one or any combination of Examples1-7, wherein when the HE PPM is generated for a normal mode the targetsymbol power of the L-LTF symbol period may be equal to the targetsymbol power for the L-SIG symbol period; the processing circuitry maybe further configured to scale the per-subcarrier power of the L-LTFpilot symbols and the per-subcarrier power of the L-SIG extension pilotsymbols by a factor of 1/52 with respect to the target symbol power forthe L-LTF; and the processing circuitry may be further configured toscale the per-subcarrier power of the L-LTF legacy symbols by a productof 1/52 and 48/52 with respect to the target symbol power for the L-LTF.

In Example 9, the subject matter of one or any combination of Examples1-8, wherein when the HE PPDU is generated for an extended coveragemode: the target symbol power of the L-LTF symbol period may be twicethe target symbol power for the L-SIG symbol period; the processingcircuitry may be further configured to scale the per-subcarrier power ofthe L-LTF pilot symbols and the per-subcarrier power of the L-SIGextension pilot symbols by a factor of 1/52 with respect to the targetsymbol power for the L-LTF; and the processing circuitry may be furtherconfigured to scale the per-subcarrier power of the L-LTF legacy symbolsby a product of 1/52 and 44/52 with respect to the target symbol powerfor the L-LTF.

In Example 10, the subject matter of one or any combination of Examples1-9, wherein the HE-SIG may be encoded for transmission during an HE-SIGsymbol period of the HE PPDU. The processing circuitry may be furtherconfigured to, when the HE PPDU is generated for transmission in anextended coverage mode: boost the target symbol power for the L-LTFsymbol period by three decibels (dB) relative to a target symbol powerof the HE-SIG; scale the per-subcarrier power of the L-SIG extensionpilot symbols to match the per-subcarrier power of the L-LTF pilotsymbols; and scale the legacy symbols of the L-SIG to a per-subcarrierpower that is three dB lower than the per-subcarrier power of the L-LTFpilot symbols.

In Example 11, the subject matter of one or any combination of Examples1-10, wherein the HE-SIG may be an HE-SIG-A field or an HE-SIG-B field.The L-SIG may be an L-SIG field or a repeated L-SIG (RL-SIG) field. TheHE PPDU may include the L-LTF in a first symbol period, an L-SIGfollowing the L-LTF, an RL-SIG following the L-SIG, an HE-SIG-Afollowing the RL-SIG, and an HE-SIG-B following the HE-SIG-A.

In Example 12, the subject matter of one or any combination of Examples1-11, wherein the HE-SIG symbols may be based on control information forone or more HE data fields included in the HE PPDU. The processingcircuitry may be further configured to scale a per-subcarrier power ofthe HE-SIG symbols to match the per-subcarrier power of the L-LTF pilotsymbols and the per-subcarrier power of the L-SIG extension pilotsymbols.

In Example 13, the subject matter of one or any combination of Examples1-12, wherein the processing circuitry may be further configured tocontend for a wireless medium during a contention period to receiveexclusive control of the medium during a transmission opportunity(TXOP). The HE PPDU may be transmitted during the TXOP.

In Example 14, the subject matter of one or any combination of Examples1-13, wherein the processing circuitry may include a baseband processorto generate the HE PPDU.

In Example 15, the subject matter of one or any combination of Examples1-14, wherein the apparatus may further include a transceiver totransmit the HE PPDU.

In Example 16, a non-transitory computer-readable storage medium maystore instructions for execution by one or more processors to performoperations for communication by an access point (AP). The operations mayconfigure the one or more processors to encode, for transmission as partof a high-efficiency (HE) physical layer convergence procedure (PLCP)protocol data unit (PPDU), a legacy long training field (L-LTF) based onL-LTF pilot symbols mapped to a group of legacy subcarriers during anL-LTF symbol period. The operations may further configure the one ormore processors to encode, for transmission as part of the HE PPDU, alegacy signal field (L-SIG) based on L-SIG legacy symbols mapped to thelegacy subcarriers during an symbol period and further based on L-SIGextension pilot symbols mapped to a group of HE extension subcarriersduring the L-SIG symbol period. The operations may further configure theone or more processors to match per-subcarrier powers of the L-SIGextension pilot symbols and the L-LTF pilot symbols. The operations mayfurther configure the one or more processors to scale the L-SIG legacysymbols and L-SIG extension pilot symbols in accordance with anormalized power restriction for the L-SIG symbol period.

In Example 17, the subject matter of Example 16, wherein the operationsmay further configure the one or more processors to encode, fortransmission as part of the HE PPDU, an HE signal field (HE-SIG) basedon HE-SIG symbols mapped to the legacy subcarriers and the HE extensionsubcarriers during an HE-SIG symbol period. The HE-SIG symbols may bebased on control information for one or more HE data fields included inthe HE PPDU.

In Example 18, the subject matter of one or any combination of Examples16-17, wherein the L-SIG extension pilot symbols may enable anextension, by a station (STA), of a legacy channel estimate of thelegacy subcarriers based on the L-LTF pilot symbols to include a channelestimate of the HE extension subcarriers.

In Example 19, a method of communication by an access point (AP) maycomprise generating, for transmission, a high-efficiency (HE) physicallayer convergence procedure (PLCP) protocol data unit (PPDU) thatincludes a legacy long training field (L-LTF), a legacy signal field(L-SIG), and an HE signal field (HE-SIG), The L-LTF may be based onL-LTF pilot symbols mapped to a group of legacy subcarriers. The HE-SIGmay be based on HE-SIG symbols mapped to a group of HE subcarriers thatincludes the legacy subcarriers and a group of HE extension subcarriers.The L-SIG may be based on L-SIG legacy symbols mapped to the legacysubcarriers and may be further based on L-SIG extension pilot symbolsmapped to the HE extension subcarriers. A per-subcarrier power of theL-SIG extension pilot symbols may be scaled to match a per-subcarrierpower of the L-LTF pilot symbols.

In Example 20, the subject matter of Example 19, wherein the L-SIGextension pilot symbols may enable a determination of an extendedchannel estimate of both the legacy subcarriers and the HE extensionsubcarriers in comparison to a legacy channel estimate of the legacysubcarriers based on the L-LTF pilot symbols.

In Example 21, an apparatus of a station (STA) may comprise memory. Theapparatus may further comprise processing circuitry. The processingcircuitry may be configured to determine, based on a high-efficiency(HE) physical layer convergence procedure (PLCP) protocol data unit(PPDU) received from an access point (AP), channel estimates of a groupof HE subcarriers that includes legacy subcarriers and HE extensionsubcarriers. The processing circuitry may be further configured todecode, in accordance with the channel estimates, an HE signal field(HE-SIG) based on HE-SIG symbols mapped to the HE subcarriers. Thechannel estimates of the legacy subcarriers may be based at least partlyon legacy long training field (L-LTF) pilot symbols of an L-LTF of theHE PPDU. The channel estimates of the HE extension subcarriers may bebased on legacy signal field (L-SIG) extension pilot symbols of an L-SIGof the HE PPDU. The channel estimates may be determined based on matchedper-subcarrier transmission powers of the L-LTF pilot symbols and theL-SIG extension pilot symbols.

In Example 22, the subject matter of Example 21, wherein the L-LTF pilotsymbols may be mapped to the legacy subcarriers in an L-LTF symbolperiod of the HE PPDU. The L-SIG extension pilot symbols may be mappedto the HE extension subcarriers in an L-SIG symbol period of the HE PPDUthat follows the L-LTF symbol period. HE-SIG symbols may be mapped tothe HE subcarriers in an HE-SIG symbol period of the HE PPDU thatfollows the L-SIG symbol period. The processing circuitry may be furtherconfigured to decode, in accordance with the channel estimates of thelegacy subcarriers, L-SIG legacy symbols mapped to the legacysubcarriers in the L-SIG symbol period.

In Example 23, the subject matter of one or any combination of Examples21-22, wherein the HE PPDU may be received in channel resources of 20MHz. The channel resources may include 64 subcarriers of 312.5 kHz. Thechannel resources may include a lower guard band at a lower edge of thechannel resources, followed by two HE extension subcarriers, followed by26 legacy subcarriers, followed by a DC subcarrier, followed by 26legacy subcarriers, followed by two HE extension subcarriers, followedby an upper guard band at an upper edge of the channel resources.

In Example 24, the subject matter of one or any combination of Examples21-23, wherein the processing circuitry may include a baseband processorto determine the channel estimates and to decode the HE-SIG.

In Example 25, the subject matter of one or any combination of Examples21-24, wherein the apparatus may further include a transceiver toreceive the HE PPDU.

In Example 26, an apparatus of an access point (AP) may comprise meansfor encoding, for transmission as part of a high-efficiency (HE)physical layer convergence procedure (PLCP) protocol data unit (PPDU), alegacy long training field (L-LTF) based on L-LTF pilot symbols mappedto a group of legacy subcarriers during an L-LIT symbol period. Theapparatus may further comprise means for encoding, for transmission aspart of the HE PPDU, a legacy signal field (L-SIG) based on L-SIG legacysymbols mapped to the legacy subcarriers during an L-SIG symbol periodand further based on L-SIG extension pilot symbols mapped to a group ofHE extension subcarriers during the L-SIG symbol period. The apparatusmay further comprise means for matching per-subcarrier powers of theL-SIG extension pilot symbols and the L-LIT pilot symbols. The apparatusmay further comprise means for scaling the L-SIG legacy symbols andL-SIG extension pilot symbols in accordance with a normalized powerrestriction for the L-SIG symbol period.

In Example 27, the subject matter of Example 26, wherein the apparatusmay further comprise means for encoding, for transmission as part of theHE PPDU, an HE signal field (HE-SIG) based on HE-SIG symbols mapped tothe legacy subcarriers and the HE extension subcarriers during an HE-SIGsymbol period. The HE-SIG symbols may be based on control informationfor one or more HE data fields included in the HE PPDU.

In Example 28, the subject matter of one or any combination of Examples26-27, wherein the L-SIG extension pilot symbols may enable anextension, by a station (STA), of a legacy channel estimate of thelegacy subcarriers based on the L-LTF pilot symbols to include a channelestimate of the HE extension subcarriers.

The Abstract is provided to comply with 37 C.F.R. Section 1.72(b)requiring an abstract that will allow the reader to ascertain the natureand gist of the technical disclosure. It is submitted with theunderstanding that it will not be used to limit or interpret the scopeor meaning of the claims. The following claims are hereby incorporatedinto the detailed description, with each claim standing on its own as aseparate embodiment.

What is claimed is:
 1. An apparatus of an access point (AP), theapparatus comprising: memory; and processing circuitry configured to:encode, for transmission, a legacy long training field (L-LTF) based onL-LTF pilot symbols mapped to a group of legacy subcarriers; scale aper-subcarrier power for a group of legacy signal (L-SIG) extensionpilot symbols to match a per-subcarrier power of the L-LTF pilotsymbols; encode, for transmission, an L-SIG field based on L-SIG legacysymbols mapped to the legacy subcarriers and further based on the scaledL-SIG extension pilot symbols mapped to a group of high efficiency (HE)extension subcarriers; encode, for transmission, an HE signal field(HE-SIG) based on HE-SIG symbols mapped to a group of HE subcarriersthat includes the legacy subcarriers and the HE extension subcarriers;and generate, for transmission, an HE physical layer convergenceprocedure (PLCP) protocol data unit (PPDU) to include the L-LTF, theL-SIG, and the HE-SIG.
 2. The apparatus according to claim 1, whereinthe L-SIG extension pilot symbols are to enable a determination of anextended channel estimate of both the legacy subcarriers and the HEextension subcarriers in comparison to a legacy channel estimate of thelegacy subcarriers based on the L-LTF pilot symbols.
 3. The apparatusaccording to claim 1, wherein: the processing circuitry is furtherconfigured to generate the HE PPDU for transmission in channel resourcesof 20 MHz, the channel resources include 64 subcarriers of 312.5 kHz,and the channel resources include a lower guard band at a lower edge ofthe channel resources, followed by two HE extension subcarriers,followed by 26 legacy subcarriers, followed by a DC subcarrier, followedby 26 legacy subcarriers, followed by two HE extension subcarriers,followed by an upper guard band at an upper edge of the channelresources.
 4. The apparatus according to claim 1, wherein the processingcircuitry is further configured to boost the per-subcarrier power of theL-SIG extension pilot symbols, with respect to a per-subcarrier power ofthe L-SIG legacy symbols, to match the per-subcarrier power of the L-LTFpilot symbols.
 5. The apparatus according to claim 4, wherein: the L-SIGis encoded for transmission during an L-SIG symbol period of the HEPPDU, and the processing circuitry is further configured to scale theper-subcarrier power of the L-SIG legacy symbols based on theper-subcarrier power of the L-SIG extension pilot symbols and anormalized power restriction for the L-SIG symbol period.
 6. Theapparatus according to claim 1, wherein: the L-LTF is encoded fortransmission during an L-LTF symbol period of the HE PPDU, the isencoded for transmission during an L-SIG symbol period of the HE PPDUthat follows the L-LTF symbol period, the processing circuitry isfurther configured to scale the per-subcarrier power of the L-LTF pilotsymbols in accordance with a target symbol power for the L-LTF symbolperiod, and the processing circuitry is further configured to scale theper-subcarrier power of the L-SIG extension pilot symbols and theper-subcarrier power of the L-SIG legacy symbols in accordance with atarget symbol power for the L-SIG symbol period.
 7. The apparatusaccording to claim 6, wherein: the HE subcarriers are of predeterminedbandwidth of 312.5 kHz and are included in channel resources of 20 MHz,the group of legacy subcarriers includes 52 subcarriers and the group ofHE extension subcarriers includes four subcarriers, the L-SIG is basedon 52 legacy symbols and four L-SIG extension pilot symbols, and theL-LTF is based on 52 L-LTF pilot symbols.
 8. The apparatus according toclaim 7, wherein: when the HE PPDU is generated for a normal mode: thetarget symbol power of the L-LTF symbol period is equal to the targetsymbol power for the L-SIG symbol period, the processing circuitry isfurther configured to scale the per-subcarrier power of the L-LTF pilotsymbols and the per-subcarrier power of the L-SIG extension pilotsymbols by a factor of 1/52 with respect to the target symbol power forthe L-LTF, and the processing circuitry is further configured to scalethe per-subcarrier power of the L-LTF legacy symbols by a product of1/52 and 48/52 with respect to the target symbol power for the L-LTF. 9.The apparatus according to claim 8, wherein: when the HE PPM isgenerated for an extended coverage mode: the target symbol power of theL-LTF symbol period is twice the target symbol power for the symbolperiod, the processing circuitry is further configured to scale theper-subcarrier power of the L-LTF pilot symbols and the per-subcarrierpower of the L-SIG extension pilot symbols by a factor of 1/52 withrespect to the target symbol power for the L-LTF, and the processingcircuitry is further configured to scale the per-subcarrier power of theL-LTF legacy symbols by a product of 1/52 and 44/52 with respect to thetarget symbol power for the L-LTF.
 10. The apparatus according to claim7, wherein: the HE-SIG is encoded for transmission during an HE-SIGsymbol period of the HE PPDU, the processing circuitry is furtherconfigured to, when the HE PPDU is generated for transmission in anextended coverage mode: boost the target symbol power for the L-LTFsymbol period by three decibels (dB) relative to a target symbol powerof the HE-SIG; scale the per-subcarrier power of the L-SIG extensionpilot symbols to match the per-subcarrier power of the L-LTF pilotsymbols; and scale the legacy symbols of the L-SIG to a per-subcarrierpower that is three dB lower than the per-subcarrier power of the L-LTFpilot symbols.
 11. The apparatus according to claim 1, wherein: theHE-SIG is an HE-SIG-A field or an HE-SIG-B field, the L-SIG is an L-SIGfield or a repeated L-SIG (RL-SIG) field, and the HE PPDU includes theL-LTF in a first symbol period, an L-SIG following the L-LTF, an RL-SIGfollowing the L-SIG, an HE-SIG-A following the RL-SIG, and an HE-SIG-Bfollowing the HE-SIG-A.
 12. The apparatus according to claim 1, wherein:the HE-SIG symbols are based on control information for one or more HEdata fields included in the HE PPDU, and the processing circuitry isfurther configured to scale a per-subcarrier power of the HE-SIG symbolsto match the per-subcarrier power of the L-LTF pilot symbols and theper-subcarrier power of the L-SIG extension pilot symbols.
 13. Theapparatus according to claim 1, the processing circuitry furtherconfigured to: contend for a wireless medium during a contention periodto receive exclusive control of the medium during a transmissionopportunity (TXOP), wherein the HE PPDU is to be transmitted during theTXOP.
 14. The apparatus according to claim 1, wherein the processingcircuitry includes a baseband processor to generate the HE PPDU.
 15. Theapparatus according to claim 1, wherein the apparatus further includes atransceiver to transmit the HE PPDU.
 16. A non-transitorycomputer-readable storage medium that stores instructions for executionby one or more processors to perform operations for communication by anaccess point (AP), the operations to configure the one or moreprocessors to: encode, for transmission as part of a high-efficiency(HE) physical layer convergence procedure (PLCP) protocol data unit(PPDU), a legacy long training field (L-LTF) based on L-LTF pilotsymbols mapped to a group of legacy subcarriers during an L-LTF symbolperiod; encode, for transmission as part of the HE PPDU, a legacy signalfield (L-SIG) based on L-SIG legacy symbols mapped to the legacysubcarriers during an L-SIG symbol period and further based on L-SIGextension pilot symbols mapped to a group of HE extension subcarriersduring the L-SIG symbol period; match per-subcarrier powers of the L-SIGextension pilot symbols and the L-LTF pilot symbols; and scale the L-SIGlegacy symbols and L-SIG extension pilot symbols in accordance with anormalized power restriction for the L-SIG symbol period.
 17. Thenon-transitory computer-readable storage medium according to claim 16,the operations to further configure the one or more processors to:encode, for transmission as part of the HE PPDU, an HE signal field(HE-SIG) based on HE-SIG symbols mapped to the legacy subcarriers andthe HE extension subcarriers during an HE-SIG symbol period, wherein theHE-SIG symbols are based on control information for one or more HE datafields included in the HE PPDU.
 18. The non-transitory computer-readablestorage medium according to claim 16, wherein the L-SIG extension pilotsymbols are to enable an extension, by a station (STA), of a legacychannel estimate of the legacy subcarriers based on the L-LTF pilotsymbols to include a channel estimate of the HE extension subcarriers.19. A method of communication by an access point (AP), the methodcomprising: generating, for transmission, a high-efficiency (HE)physical layer convergence procedure (PLCP) protocol data unit (PPDU)that includes a legacy long training field (L-LTF), a legacy signalfield (L-SIG), and an HE signal field (HE-SIG), wherein the L-LTF isbased on L-LTF pilot symbols mapped to a group of legacy subcarriers,wherein the HE-SIG is based on HE-SIG symbols mapped to a group of HEsubcarriers that includes the legacy subcarriers and a group of HEextension subcarriers, wherein the L-SIG is based on L-SIG legacysymbols mapped to the legacy subcarriers and is further based on L-SIGextension pilot symbols mapped to the HE extension subcarriers, andwherein a per-subcarrier power of the L-SIG extension pilot symbols isscaled to match a per-subcarrier power of the L-LTF pilot symbols. 20.The method according to claim 19, wherein the L-SIG extension pilotsymbols are to enable a determination of an extended channel estimate ofboth the legacy subcarriers and the HE extension subcarriers incomparison to a legacy channel estimate of the legacy subcarriers basedon the L-LTF pilot symbols.
 21. An apparatus of a station (STA), theapparatus comprising: memory; and processing circuitry configured to:determine, based on a high-efficiency (HE) physical layer convergenceprocedure (PLCP) protocol data unit (PPDU) received from an access point(AP), channel estimates of a group of HE subcarriers that includeslegacy subcarriers and HE extension subcarriers; and decode, inaccordance with the channel estimates, an HE signal field (HE-SIG) basedon HE-SIG symbols mapped to the HE subcarriers, wherein the channelestimates of the legacy subcarriers are based at least partly on legacylong training field (L-LTF) pilot symbols of an L-LTF of the HE PPDU,wherein the channel estimates of the HE extension subcarriers are basedon legacy signal field (L-SIG) extension pilot symbols of an L-SIG ofthe HE PPDU, and wherein the channel estimates are determined based onmatched per-subcarrier transmission powers of the L-LTF pilot symbolsand the L-SIG extension pilot symbols.
 22. The apparatus according toclaim 21, wherein: the pilot symbols are mapped to the legacysubcarriers in an L-LTF symbol period of the HE PPDU, the L-SIGextension pilot symbols are mapped to the HE extension subcarriers in anL-SIG symbol period of the HE PPDU that follows the L-LTF symbol period,HE-SIG symbols are mapped to the HE subcarriers in an HE-SIG symbolperiod of the HE PPDU that follows the L-SIG symbol period, theprocessing circuitry is further configured to decode, in accordance withthe channel estimates of the legacy subcarriers, L-SIG legacy symbolsmapped to the legacy subcarriers in the L-SIG symbol period.
 23. Theapparatus according to claim 21, wherein: the HE PPDU is received inchannel resources of 20 MHz, the channel resources include 64subcarriers of 312.5 kHz, and the channel resources include a lowerguard band at a lower edge of the channel resources, followed by two HEextension subcarriers, followed by 26 legacy subcarriers, followed by aDC subcarrier, followed by 26 legacy subcarriers, followed by two HEextension subcarriers, followed by an upper guard band at an upper edgeof the channel resources.
 24. The apparatus according to claim 21,wherein the processing circuitry includes a baseband processor todetermine the channel estimates and to decode the HE-SIG.
 25. Theapparatus according to claim 21, wherein the apparatus further includesa transceiver to receive the HE PPDU.